Catheter shape release mechanism

ABSTRACT

A catheter includes a handle, a catheter sheath and a stylet having a shaped distal part received within the catheter sheath. The catheter includes a catheter shape release mechanism comprising the catheter handle and an elongate catheter sheath carrier. The catheter sheath carrier is slidable between a first position in which the shaped distal part of the stylet lies in register with the distal part of the catheter sheath to impart that shape to the catheter sheath and a second position in which the shaped distal part of the stylet is located proximally of the distal part of the catheter sheath. The catheter shape release mechanism enables retraction of the handle and the stylet while keeping the catheter sheath in place in case the catheter snags on tissue when in use.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase entry under 35 U.S.C. §371 ofInternational Patent Application PCT/AU2011/000531, filed May 10, 2011,designating the United States of America and published in English asInternational Patent Publication WO 2011/140585 A1 on Nov. 17, 2011,which claims the benefit under Article 8 of the Patent CooperationTreaty and under 35 U.S.C. §119(e) to U.S. Provisional PatentApplication Ser. No. 61/333,593, filed May 11, 2010, the disclosure ofeach of which is hereby incorporated herein by this reference in itsentirety.

TECHNICAL FIELD

This disclosure relates, generally, to a catheter and, moreparticularly, to a catheter shape release mechanism and to a catheterincluding such shape release mechanism.

BACKGROUND

Any discussion of the prior art throughout the specification should inno way be considered as an admission that such prior art is widely knownor forms part of common general knowledge in the field.

Catheters are commonly used in medical practice to examine and treat theheart. They may be inserted into the cardiovascular system of thepatient through small punctures in the skin, usually in the neck orgroin area. Typically, a catheter includes a catheter sheath carryingseveral electrodes at the tip of the sheath and a control handle fordeflecting the tip of the catheter to steer or guide the catheter. Theelectrodes attached to the catheter sheath can be used to senseelectrical signals to identify particular heart conditions or to treatthese conditions.

Some catheters carry a multi-electrode loop or lasso structure at thetip of the catheter sheath. One of the advantages of the multi-electrodeloop structure is that sensing can be achieved over a larger area. Forexample, electrical signals can be sensed around an entire pulmonaryvein. A catheter, particularly a loop catheter, can sometimes snag ontissue when it is inserted in the vascular system of the patient. Inthese circumstances, the physician usually tries to free the catheter bypushing or pulling the catheter gently within the vein. Aggressiveretraction of the catheter, however, may cause undesirable and dangeroustearing of the tissue or possibly even fracturing of the cathetersheath.

DISCLOSURE

It is an object of the present invention to overcome or ameliorate atleast one of the disadvantages of the prior art, or to provide a usefulalternative.

According to an embodiment of the invention, there is provided acatheter shape release mechanism that includes a catheter handle havinga handle body defining a proximal end and an opposed distal end with apassage extending between the proximal end and the distal end, aninterior of the catheter handle being configured to receive a proximalpart of a stylet (during use, the stylet protrudes from the distal endof the handle body), the stylet having a distal part that is formed intoa predetermined shape, and an elongate catheter sheath carrier slidablyreceived in the passage of the handle body to protrude through thedistal end of the handle body, a catheter sheath being receivable overthe stylet and mountable to the carrier (while in use, extends from adistal end of the carrier), the carrier being slidable between a firstposition in which the shaped distal part of the stylet lies in registerwith a distal part of the catheter sheath to impart that shape to thecatheter sheath and a second position in which the shaped distal part ofthe stylet is located proximally of the distal part of the cathetersheath.

The catheter handle and the carrier may include complementary guideformations for guiding displacement of the carrier relative to thecatheter handle. The complementary guide formations may include alocking arrangement for locking the carrier at least in its firstposition relative to the catheter handle. The guide formations may alsocomprise a guide slot associated with one of the catheter handle and thecarrier and a guide follower carried by the other of the catheter handleand the carrier. The locking arrangement may further include a detentfor restraining the carrier against movement from its first position.

In an embodiment, the catheter sheath carrier comprises a sleevereceivable through an opening at the distal end of the handle body, thesleeve defining a bore through which a proximal region of the cathetersheath can pass during use. The carrier may also include a supportmember for supporting the proximal region of the catheter sheath. Thesleeve may further comprise a plurality of parts that are assembledtogether to form the sleeve and that can be disassembled to gain accessto the support member and the catheter sheath during use to facilitateremoval of the catheter sheath from the catheter handle. In addition,the carrier may include a strain relief that may be removably mounted tothe distal end of the sleeve to facilitate removal of the strain relieffrom the sleeve. The strain relief may further be of a resilientlyflexible material to inhibit ingress of foreign material into theinterior of the sleeve.

In an embodiment, the handle comprises a plurality of shell parts thatcan be at least partially separated to allow access to an interior ofthe handle.

In another embodiment, there is provided a method of fabricating acatheter shape release mechanism as described above.

According to yet another embodiment, there is provided a catheter thatincludes a catheter handle having a handle body defining a proximal endand an opposed distal end with a passage extending between the proximalend and the distal end, a stylet mounted to the catheter handle toprotrude through the distal end of the catheter handle, an interior ofthe catheter handle being configured to receive a proximal part of thestylet, the stylet having a distal part that is formed into apredetermined shape, an elongate catheter sheath carrier slidablyreceived in the passage of the handle body to protrude through thedistal end of the handle body, and a catheter sheath received over thestylet and mounted to the carrier to extend from a distal end of thecarrier, the carrier being slidable between a first position in whichthe shaped distal part of the stylet lies in register with a distal partof the catheter sheath to impart that shape to the catheter sheath and asecond position in which the shaped distal part of the stylet is locatedproximally of the distal part of the catheter sheath.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings in which:

FIG. 1 shows a three-dimensional view of a catheter with a shape releasemechanism in an inoperative position;

FIG. 2 shows a three-dimensional view of the catheter with the shaperelease mechanism in an operative position;

FIG. 3 shows a three-dimensional, exploded view of the catheter sheathcarrier of the catheter shape release mechanism together with thecatheter sheath;

FIG. 4 shows a cross-sectional bottom view of a part of a steeringcontrol mechanism of the catheter handle carrying a component of theshape release mechanism;

FIG. 5 shows a three-dimensional, exploded view of the steering controlmechanism and shape release mechanism of the catheter;

FIG. 6 shows a cross-sectional side view of a handle of the catheterwith the shape release mechanism in its inoperative position;

FIG. 7 shows a cross-sectional side view of a handle of the catheterwith the shape release mechanism in its operative position;

FIG. 8 shows a three-dimensional, exploded view of a handle of thecatheter;

FIG. 9 shows a plan view of a proximal part of a stylet of the catheter;

FIG. 10 shows a plan view of a part of a shape adjustment mechanism ofthe catheter;

FIG. 11 shows a three-dimensional view of a part of the handle showingthe interrelationship between the proximal part of the stylet and theshape adjustment mechanism;

FIG. 12 shows a three-dimensional view of a distal part of the stylet;

FIG. 13 shows a three-dimensional view of a distal part of an outer tubeof the stylet; and

FIG. 14 shows a three-dimensional, exploded view of another embodimentof the handle of the catheter.

DETAILED DESCRIPTION

In the drawings, reference numeral 10 generally designates an embodimentof a catheter. The catheter 10 comprises a catheter handle 12 from whicha catheter sheath or electrode sheath 14 projects. The catheter sheath14 carries a plurality of electrodes 16 at a distal part 18 of thecatheter sheath 14. The electrodes 16 are used for diagnostic and/ortherapeutic purposes.

The catheter further includes a stylet 20 (shown in FIGS. 9 and 11-13).A proximal part 22 of the stylet 20 is received within the catheterhandle 12 as will be described in greater detail below. The cathetersheath 14 has a lumen (not shown) in which the stylet 20 is received. Asshown more clearly in FIG. 12, a distal part 24 of the stylet 20 ispre-formed into a shape, more particularly a loop shape 26. However, itwill be appreciated that the distal part 24 of the stylet could bepre-formed into any other non-rectilinear shape such as, for example, ahelix, a tapering helix, a pig tail shape, or any other desired shape.

The stylet 20 fits within the lumen of the catheter sheath 14 and theloop shape 26 of the distal part 24 of the stylet 20 is imparted to thedistal part 18 of the catheter sheath 14 as shown in FIG. 1. For ease ofexplanation, the disclosure will be described with reference to theshape at the distal part 24 of the stylet 20 being the loop shape.However, it will be appreciated that what follows could be applicable toany other stylet 20 having a shaped distal part 24.

In an embodiment, the catheter 10 includes a shape release mechanism 28.The shape release mechanism 28 comprises the catheter handle 12 and anelongate catheter sheath carrier in the form of a sleeve 30, which isslidably received in the handle 12 to protrude distally from the handle12. The shape release mechanism 28 enables releasing the shape that thestylet 20 imparts on the distal part 18 of the catheter sheath 14. Thisis achieved by pushing the catheter sheath forward so that the distalpart of the stylet 20 relocates to a position proximal to the distalpart 18 of the electrode sheath as shown at 80 in FIG. 2. In thisoperative position, the distal part of the stylet 20 and the distal part18 of the catheter sheath are no longer in register with one another.FIG. 2 shows the catheter shape release mechanism 28 in its operativeposition when the catheter sheath 14 has been pushed forward and thedistal parts of the catheter sheath 14 and the stylet 20 are no longerin register with one another.

The handle 12 comprises a handle body 32. The handle body 32 is made upof a plurality of shell parts 34, shown most clearly in FIG. 8. In theillustrated embodiment, the handle body 32 comprises two shell partsthat are substantially mirror images of each other. The handle body 32has a proximal end 36 and a distal end 38. A passage 40 (FIG. 8) extendsbetween the proximal end 36 and the distal end 38 of the handle body 32.

In the embodiment illustrated in FIG. 8, the two shell parts 34 aresecured together by clips 42, carried on one of the shell parts 34,which are received in complementary receiving formations 44 in the othershell parts 34.

In the embodiment shown in FIG. 14, only one side of each shell part 34has the clips 42 or receiving formations 44, as the case may be. Theother side of the shell parts 34 of the handle body 32 are hingedtogether with wings 46 of the hinges shown in FIG. 14.

Regardless of the manner in which the shell parts 34 connect together,it is a simple process to open the handle body 32 by disengaging theshell parts 34 to enable access to be gained to an interior of thehandle body 32. Further, it will be appreciated that, instead of clips,the shell parts 34 could be held together in other ways, for example, bybeing screwed together, by means of one or more spring clips receivedabout the handle body 32, or the like.

With reference to FIG. 3, the sleeve 30 of the shape release mechanism28 comprises two parts 48. In the illustrated embodiment, the two parts48 clip together via clips 50 and locating formations 52. As describedabove with reference to the shell parts 34 of the handle body 32, itwill be appreciated that these parts 48 could also be hinged togetherand clipped or screwed together to form the sleeve 30.

The sleeve 30 surrounds a support member 54 for supporting the cathetersheath 14. The support member 54 has a longitudinally extending channel56 formed in it. A proximal part 58 of the catheter sheath 14 issupported in the channel 56 of the support member 54. If desired, theproximal part 58 can be bonded in the channel 56 by means of a suitableadhesive.

The shape release mechanism 28 also includes a strain relief 60. In theembodiment shown in the accompanying figures, the strain relief isconically shaped to allow the catheter sheath to move and bend withoutputting stress on the connection where the catheter sheath 14 meets thesleeve 30 of the shape release mechanism. The strain relief 60 issecured to a distal end 62 (FIGS. 1 and 2) of the sleeve 30. The strainrelief 60 is of a resiliently flexible material and has a proximalcollar 64, which engages a shoulder 66 on the parts 48 of the sleeve 30to hold the strain relief captive when the parts 48 of the sleeve 30 aresecured together. The strain relief 60, being of a resiliently flexiblematerial, also inhibits ingress of foreign matter, such as bodily fluidinto the interior of the sleeve 30 and, therefore, the interior of thecatheter handle 12.

The shape release mechanism 28 includes complementary guide formationsfor guiding sliding displacement of the sleeve 30 relative to the handlebody 32. The complementary guide formations comprise a pin 68 arrangedat a proximal end of one of the parts 48 of the sleeve 30. A guide plate70 (FIG. 4) is secured to a part of the catheter handle 12, moreparticularly, a steering control mechanism 72 of the catheter handle 12.The steering control mechanism 72 will be described in greater detailbelow.

The guide plate 70 defines a guide slot 74 that extends axially in theguide plate 70. The guide slot 74 is cranked and a locking arrangementin the form of a detent 76 is defined at a proximal end of the guideslot 74. Thus, when the sleeve 30 is in its retracted position as shownin FIG. 1, the pin 68 is received in the detent 76 at an extremity 78.To release the sleeve 30 to enable it to slide axially to the positionas shown in FIG. 2, the sleeve 30 needs to be rotated so that the pin 68moves away from the extremity 78 into alignment with the remainder ofthe guide slot 74. The sleeve 30 is then free to be extended to theposition as shown in FIG. 2.

The purpose of the shape release mechanism 28 is to release the loopshape 26 when it snags on tissue in the patient's body during use. Thiscan lead to complications and difficulty. As shown, the loop shape 26 isa tightly wound formation. However, by extending the catheter sheath 14relative to the stylet 20 from the position shown in FIG. 1 to theposition shown in FIG. 2, by extending the sleeve 30 relative to thehandle 12, the distal part 24 of the stylet 20 is withdrawn from thedistal part 18 of the catheter sheath 14 and adopts a position proximalthe distal part 18 of the catheter sheath 14 as shown at 80 in FIG. 2.When the distal part 24 of the stylet 20 is withdrawn proximallyrelative to the distal part 18 of the catheter sheath 14, the tension inthe distal part 24 of the stylet is reduced, causing the distal part toadopt a more drawn out, less tightly wound shape and facilitatesdisentanglement or release of the shaped part of the catheter sheath 14from tissue in which it may have become entangled. In practice, if theloop structure of the catheter snags on tissue, the user would unlockthe locking arrangement, keeping the catheter sheath carrier sleeve 30in place, and then pull back the catheter handle and the stylet whilekeeping the sleeve 30 in place. This way, the distal tip of the cathetersheath stays in place where it snagged on tissue and once the loop ofthe stylet is pulled back, the sheath becomes free again. It is alsopossible to reduce the size of the loop structure to assist in releasingthe loop from the tissue by appropriate manipulation of thesize-adjusting mechanism 128 described in more detail below.

As described above, the catheter handle 12 includes a steering controlmechanism 72. This steering control mechanism 72 is used for steeringthe distal part of the catheter sheath 18 through the patient'svasculature and, also, for effecting deflection of the loop formation 26at the distal part of the catheter sheath 14.

Before describing the steering control mechanism 72 in greater detail,the stylet 20 will also be described to understand the operation of thestylet 20 of the catheter 10. FIG. 9 shows a proximal part of the stylet20 when it is not connected to the catheter handle, and FIG. 11 showsthe proximal part of the stylet mounted in one of the shell parts 34 ofthe handle body 32 of the catheter handle 12. FIG. 12 shows a distalpart of the stylet 20 and FIG. 13 shows a distal part of a component ofthe stylet 20 in the form of an outer tubular member 82.

The outer tubular member 82 has a distal part 84, which is shown ingreater detail in FIG. 13. The distal part 84 of the outer tubularmember 82 is pre-formed into the loop-shape 26 and has a distal end 86.The distal part 84 is cranked as shown at 88 so that the loop shape 26lies in a plane transverse or perpendicular to a longitudinal axis ofthe outer tubular member 82. An elongate, cutaway, bend-enhancingportion 90 is formed in the distal part 84 of the tubular member 82proximal to the cranked region 88. The portion 90 is a scalloped portionand has varying amounts cut away, increasing from the proximal end tothe distal end of the cutaway portion 90 to facilitate deflection of thedistal end of the loop shape 26 of the stylet 20, as will be describedin greater detail below.

The stylet 20 also includes an inner, tubular actuator 92 (shown in FIG.12). The actuator 92 has a distal end secured at 94 to the distal part84 of the outer tubular member 82 of the stylet 20. It is to be notedthat the connection point 94 is proximally arranged relative to thecranked portion 88 but distally arranged relative to the cutaway portion90. The tubular actuator 92 has a slotted bend-enhancing region 96,which is substantially the same length and lies coincident with thecutaway portion 90 of the outer tubular member 82 of the stylet 20.Relative movement between the outer tubular member 82 and the innertubular actuator 92 causes deflection of the loop shape 26 in thedirection of arrows 98 (FIG. 13).

A size-adjusting actuator in the form of a pull wire 100 is receivedthrough lumens of the outer tubular member 82 and the tubular actuator92 and a distal end of the pull wire 100 is fast with the distal end 86of the outer tubular member 82. It is to be noted that there is a secondlongitudinally extending cutaway portion 102 formed between the distalend 86 of the outer tubular member 82 and the cranked region 88 of theouter tubular member 82 as shown in FIG. 13. This cutaway portion 102facilitates adjustment of the size of the loop shape 26 by relativemovement between the pull wire 100 and the outer tubular member 82.

As shown in FIG. 9, a proximal end of the pull wire 100 is mounted to astylet carrier in the form of a slide 104. A proximal end of the outertubular member 82 carries a mounting sleeve 106 and, similarly, aproximal end of the tubular actuator 92 carries a mounting sleeve 108.

The steering control mechanism 72 comprises an elongate, hollowcylindrical member 110 (shown in FIG. 8) that is displaceably andpreferably slidably received within the passage 40 defined by the handlebody 32. As in the case of other components of the catheter handle 12,the cylindrical member 110 comprises two parts 112 that, in theillustrated embodiment, are clipped together via complementary clips 114and receiving formations 116. As in the case of the shell parts 34 ofthe handle body 32, the parts 112 of the cylindrical member 110 couldalso be hinged together and clipped or screwed closed.

A raised protuberance in the form of a radially outwardly extending knob118 is defined at a distal end of the steering control mechanism 72 tobe engaged by the thumb of a clinician for facilitating steering of thedistal end of the catheter sheath 14 during use. The deflection of thedistal portion 18 of the catheter sheath 12 is achieved by push/pullmotion of the control knob 118.

Referring to FIG. 11, the mounting sleeve 106 of the outer tubularmember 82 of the stylet 20 is shown mounted in a seat 120 in one of theparts 112 of the steering control mechanism 72. The other part 112 couldcontain a corresponding part of the seat 120. The outer tubular memberis thus connected to the slidable cylindrical member 110 of the steeringcontrol mechanism 72. A further seat 122 is defined proximal to the seat120 in the passage 40 of the handle body 32 and the mounting sleeve 108of the tubular actuator 92 is made fast with the seat 122. The innertubular actuator is thus made fast with the handle body 32 of thecatheter and remains in place when the outer tubular member is moved bypushing/pulling of the control knob 118. It will be appreciated that asthe steering control mechanism 72 is moved in the direction of arrows124 relative to the handle body 32, relative movement between the outertubular member 82 of the stylet 20 and the inner tubular actuator 92occurs, resulting in deflection of the distal end of the stylet 20 asshown by the arrows 98 in FIG. 13.

As illustrated in FIG. 11, the proximal part of the pull wire 100 isguided around a semispherical guidepost 126, fixedly arranged in thepassage 40 of the handle body 32, and the proximal end of the pull wire100 is mounted fast with the slide 104.

In an embodiment, the catheter 10 includes a shape, or size, adjustmentmechanism 128. The size adjustment mechanism 128 includes a sizeadjuster in the form of a collar 130 arranged on the exterior of thehandle body 32 of the catheter handle 12.

The stylet carrier 104 forms part of the size adjustment mechanism 128and is axially slidably arranged within the passage 40 of the handlebody 32 of the catheter handle 12. The collar 130 is, as with otherparts of the catheter handle 12, made up of two parts 132 that cliptogether via complementary clips 134 and receiving formations 136 (FIG.8). In another embodiment, as illustrated in FIG. 14, the parts 132 ofthe collar 130 are hinged together with a wing 138 of the hinge beingshown in FIG. 14. The other side of each part 132 clips together via theclips 134 and receiving formations 136.

As shown more clearly in FIG. 8, the shell parts 34 of the handle body32 of the catheter handle have a waisted region to define a recess 140(FIG. 8). The collar 130 is received in the recess 140 and isconstrained against axial motion but is free to rotate about alongitudinal axis of the handle body 32.

The recessed region 140 of each shell part 34 further has a cutawayportion 142 defined therein so that when the shell parts 34 are matedtogether, a longitudinally extending slot is defined in the handle body32.

The size-adjusting mechanism 128 of the catheter 10 includescomplementary guide formations in the form of a camming groove 144(shown most clearly in FIG. 10) on an internal surface of each part 132of the collar 130. A complementary guide follower in the form of a pin146 is arranged at that end of the slide 104 opposite the end to whichthe pull wire 100 is connected. The pin 146 protrudes through the slotin the handle body formed by the cutaway portions 142 of the shell parts34 and is received in the camming groove 144 of the collar 130. Rotationof the collar 130, therefore, translates into axial displacement of theslide 146. This axial displacement of the slide 146 results in relativemovement between the pull wire 100 and the outer tubular member 82 ofthe stylet 20 resulting in an increase or decrease in the size of theloop shape 26 at the distal part 24 of the stylet 20.

Thus, by rotation of the collar 130 during use, a clinician can controlthe size of the loop shape 26. This is a simple, one-handed operation.It will be appreciated that the size adjustment mechanism 128 may, inaddition or instead, operate as a second steering or deflectionmechanism.

It is possible to adjust the effort required to displace the steeringcontrol mechanism 72 relative to the handle body 32. For this purpose, africtional element 150 is provided. The frictional element 150 includesa screw 152 and washer assembly 154, the screw 152 being received in athreaded socket 156 in the shell part 34 of the handle body 32, as shownin FIG. 8. The screw protrudes through a slot 158 defined in a proximalextension limb 160 of one of the parts 112 of the cylindrical member 110of the steering control mechanism 72.

The catheter 10 includes a connector 162 arranged at the proximal end 36of the handle body 32 of the catheter handle 12. The connector 162 hasterminals 164 to which conductors (not shown) of the electrode 16 of thecatheter sheath 14 are connected. The connector 162 sits within thehandle body 32 and can be removed and replaced if necessary byseparating the shell parts 34. The connector 162 connects to a patientcable of a diagnostic/therapeutic system, with which the catheter 10 isused.

It is a particular advantage of the described embodiments that a compactcatheter handle is provided, which lends itself to one-handed use by aclinician. The handle 12 fits easily within the hand of the clinicianand all the operating controls, such as the steering control mechanism72 and the size adjustment mechanism 128, fall readily to hand. Thesteering control mechanism 72 and the size adjustment mechanism 128 areable to be manipulated one-handed by the clinician, which cliniciansprefer to do. This enables them to more easily concentrate onpositioning and operating the catheter 10.

In addition, catheters are becoming increasingly expensive. Due to theiruse in potentially biologically hazardous environments, most cathetersare used once and then disposed of. Often times, this is unnecessary andthe catheters can be re-processed. With the provision of a modular typeof handle 10, as described above, it is an easy process to access theinterior of the handle 10 to facilitate replacement or refurbishing ofthe various components and, more particularly, the catheter sheath 14,the stylet 20, as well as the connector 162. The handle 12 is a moldingof a plastics material and is generally low cost. Thus, should thehandle 12 be contaminated with bodily fluids and cannot be adequatelycleaned, it is a relatively inexpensive process to dispose of the handle12 and to replace it with a new one. Even so, because the handle 12 ismade up of modular parts, if necessary, only the contaminated parts needto be replaced.

Reference throughout this specification to “one embodiment,” “someembodiments” or “an embodiment” means that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention. Thus,appearances of the phrases “in one embodiment,” “in some embodiments” or“in an embodiment” in various places throughout this specification arenot necessarily all referring to the same embodiment, but may.Furthermore, the particular features, structures or characteristics maybe combined in any suitable manner, as would be apparent to one ofordinary skill in the art from this disclosure, in one or moreembodiments.

As used herein, unless otherwise specified, the use of the ordinaladjectives “first,” “second,” “third,” etc., to describe a commonobject, merely indicate that different instances of like objects arebeing referred to, and are not intended to imply that the objects sodescribed must be in a given sequence, either temporally, spatially, inranking, or in any other manner.

In the claims below and the description herein, any one of the terms“comprising,” “comprised of,” or “which comprises” is an open term thatmeans including at least the elements/features that follow, but notexcluding others. Thus, the term “comprising,” when used in the claims,should not be interpreted as being limitative to the means or elementsor steps listed thereafter. For example, the scope of the expression “adevice comprising” A and B should not be limited to devices consistingonly of elements A and B. Any one of the terms “including” or “whichincludes” or “that includes,” as used herein, is also an open term thatalso means including at least the elements/features that follow theterm, but not excluding others. Thus, “including” is synonymous with andmeans “comprising.”

It should be appreciated that in the above description of exemplaryembodiments of the invention, various features of the invention aresometimes grouped together in a single embodiment, figure, ordescription thereof for the purpose of streamlining the disclosure andaiding in the understanding of one or more of the various inventiveaspects. This method of disclosure, however, is not to be interpreted asreflecting an intention that the claimed invention requires morefeatures than are expressly recited in each claim.

Rather, as the following claims reflect, inventive aspects lie in lessthan all features of a single foregoing disclosed embodiment. Thus, theclaims following the Detailed Description are hereby expresslyincorporated into this Detailed Description, with each claim standing onits own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some, butnot other, features included in other embodiments, combinations offeatures of different embodiments are meant to be within the scope ofthe invention, and form different embodiments, as would be understood bythose skilled in the art. For example, in the following claims, any ofthe claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are setforth. However, it is understood that embodiments of the invention maybe practiced without these specific details. In other instances,well-known methods, structures and techniques have not been shown indetail in order not to obscure an understanding of this description.

Similarly, it is to be noticed that the term “coupled,” when used in theclaims, should not be interpreted as being limited to direct connectionsonly. The terms “coupled” and “connected,” along with their derivatives,may be used. It should be understood that these terms are not intendedas synonyms for each other. Thus, the scope of the expression “a deviceA coupled to a device B” should not be limited to devices or systemswherein an output of device A is directly connected to an input ofdevice B; it means that there exists a path between an output of A andan input of B, which may be a path including other devices or means.“Coupled” may mean that two or more elements are either in directphysical or electrical contact, or that two or more elements are not indirect contact with each other but yet still co-operate or interact witheach other.

Thus, while there has been described what are believed to be thepreferred embodiments of the invention, those skilled in the art willrecognize that other and further modifications may be made theretowithout departing from the spirit of the invention, and it is intendedto claim all such changes and modifications as falling within the scopeof the invention. For example, any formulas given above are merelyrepresentative of procedures that may be used. Functionality may beadded or deleted from the block diagrams and operations may beinterchanged among functional blocks. Steps may be added or deleted tomethods described within the scope of the present invention.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the disclosure as shownin the specific embodiments without departing from the scope of theclaims. The present embodiments are, therefore, to be considered in allrespects as illustrative and not restrictive.

1. A catheter shape release mechanism comprising: a catheter handlehaving a handle body defining a proximal end and an opposed distal endwith a passage extending between the proximal end and the distal end, aninterior of the catheter handle being configured to receive a proximalpart of a stylet, the stylet, in use, protruding from the distal end ofthe handle body and the stylet having a distal part that is formed intoa predetermined shape; and an elongate catheter sheath carrier slidablyreceived in the passage of the handle body to protrude through thedistal end of the handle body, a catheter sheath being receivable overthe stylet and mountable to the carrier, in use, to extend from a distalend of the carrier, the carrier being slidable between a first positionin which the shaped distal part of the stylet lies in register with adistal part of the catheter sheath to impart that shape to the cathetersheath and a second position in which the shaped distal part of thestylet is located proximally of the distal part of the catheter sheath.2. The shape release mechanism of claim 1, wherein the catheter handleand the carrier include complementary guide formations for guidingdisplacement of the carrier relative to the catheter handle.
 3. Theshape release mechanism of claim 2, wherein the complementary guideformations comprise a locking arrangement for locking the carrier atleast in its first position relative to the catheter handle.
 4. Theshape release mechanism of claim 3, wherein the guide formationscomprise a guide slot associated with one of the catheter handle and thecarrier and a guide follower carried by the other of the catheter handleand the carrier.
 5. The shape release mechanism of claim 3, wherein thelocking arrangement comprises a detent for restraining the carrieragainst movement from its first position.
 6. The shape release mechanismof claim 1, wherein the carrier comprises a sleeve receivable through anopening at the distal end of the handle body, the sleeve defining a borethrough which a proximal region of the catheter sheath can pass while inuse.
 7. The shape release mechanism of claim 6, wherein the carriercomprises a support member for supporting the proximal region of thecatheter sheath.
 8. The shape release mechanism of claim 7, wherein thesleeve comprises a plurality of parts that are assembled together toform the sleeve and that can be disassembled to gain access to thesupport member and the catheter sheath, in use, to facilitate removal ofthe catheter sheath from the catheter handle.
 9. The shape releasemechanism of claim 6, wherein the carrier includes a strain reliefmounted at a distal end of the sleeve.
 10. The shape release mechanismof claim 9, wherein the strain relief is removably mounted to the distalend of the sleeve to facilitate removal of the strain relief from thesleeve.
 11. The shape release mechanism of claim 9, wherein the strainrelief is of a resiliently flexible material to inhibit ingress offoreign material into the interior of the sleeve.
 12. The shape releasemechanism of claim 1, wherein the handle comprises a plurality of shellparts that can be at least partially separated to allow access to aninterior of the handle.
 13. A catheter, comprising: a catheter handlehaving a handle body defining a proximal end and an opposed distal endwith a passage extending between the proximal end and the distal end; astylet mounted to the catheter handle to protrude through the distal endof the catheter handle, an interior of the catheter handle beingconfigured to receive a proximal part of the stylet, the stylet having adistal part that is formed into a predetermined shape; an elongatecatheter sheath carrier slidably received in the passage of the handlebody to protrude through the distal end of the handle body; and acatheter sheath received over the stylet and mounted to the carrier toextend from a distal end of the carrier, the carrier being slidablebetween a first position in which the shaped distal part of the styletlies in register with a distal part of the catheter sheath to impartthat shape to the catheter sheath and a second position in which theshaped distal part of the stylet is located proximally of the distalpart of the catheter sheath.
 14. The catheter of claim 13, wherein thecatheter handle and the elongate catheter sheath carrier includecomplementary guide formations for guiding displacement of the elongatecatheter sheath carrier relative to the catheter handle.
 15. Thecatheter of claim 13, wherein the complementary guide formationscomprise a locking arrangement for locking the elongate catheter sheathcarrier at least in its first position relative to the catheter handle.16. The catheter of claim 15, wherein the guide formations comprise aguide slot associated with one of the catheter handle and the elongatecatheter sheath carrier and a guide follower carried by the other of thecatheter handle and the elongate catheter sheath carrier.
 17. Thecatheter of claim 16, wherein the locking arrangement comprises a detentfor restraining the elongate catheter sheath carrier against movementfrom its first position.
 18. The catheter of claim 13, wherein theelongate catheter sheath carrier comprises a sleeve receivable throughan opening at the distal end of the handle body, the sleeve defining abore through which a proximal region of the catheter sheath can passwhile in use.
 19. The catheter of claim 18, wherein the elongatecatheter sheath carrier comprises a support member for supporting theproximal region of the catheter sheath.
 20. The catheter of claim 19,wherein the sleeve comprises a plurality of parts that are assembledtogether to form the sleeve and that can be disassembled to gain accessto the support member and the catheter sheath, in use, to facilitateremoval of the catheter sheath from the catheter handle.